Preparation of polyolefin and its application have been remarkably developed with the aid of a catalyst, so-called Ziegler-Natta catalyst, and its production process and uses have been also developed. In particular, much of the focus has been placed on developing polyolefin products using a variety of single-site catalyst in the related art, in addition to the enhanced activity of Ziegler-Natta catalysts. As the single-site catalysts, metallocene catalysts, constrained-geometry-catalyst (CGC) from Dow, and catalysts using late transition metals are usually used.
CGC shows excellent properties in a copolymerization reaction of ethylene and alpha-olefin, compared to conventional metallocene catalysts, which can be summarized as follows.
First, CGC can be used to form high molecular weight polymers due to its high reactivity at high polymerization temperature, and second, CGC can be used for copolymerization of alpha-olefin having large steric hindrance, such as 1-hexene and 1-octene. In addition to these properties described above, due to many useful properties obtained from use of CGC, studies on synthesis of CGC derivatives as a polymerization catalyst have been substantially conducted in academic and industrial fields.
For example, synthesis of metal compounds comprising other various bridges instead of a silicon bridged CGC and a nitrogen substituent, and polymerization using these metal compounds have been tried to be performed. Examples of such metal compounds include Compounds (1) to (4) (Chem. Rev. 2003, 103, 283).

Compounds (1) to (4) contain a phosphorus bridge (1), an ethylene or propylene bridge (2), a methyllidene bridge (3), and a methylene bridge (4), respectively, instead of the silicon bridge of the CGC structure. However, these compounds show low activity or poor copolymerization performance, when ethylene is polymerized or when ethylene and alpha-olefin are copolymerized, as compared to CGC.
In addition, the amido ligand in CGC can be replaced with an oxido ligand. Some of such compounds were used for polymerization. Examples of such compounds include:

In Compound (5), which was developed by T. J. Marks et al., a cyclopentadiene Cp) derivative is bridged to an oxido ligand by ortho-penylene group (Organometallics 1997, 16, 5958). A compound having the same bridge as in Compound (5) and the polymerization using the compound were suggested by Mu et al. (Organometallics 2004, 23, 540). Further, a compound in which an indenyl ligand is bridged to an oxido ligand by an ortho-phenylene group was developed by Rothwell et al. (Chem. Commun. 2003, 1034). In Compound (6), which was developed by Whitby et al., a cyclopentadienyl ligand is bridged to an oxido ligand by three carbon atoms (Organometallics 1999, 18, 348). It was reported that Compound (6) showed reactivity in syndiotactic polystylene polymerization. Similar compounds to Compound (6) were developed by Hessen et al. (Organometallics 1998, 17, 1652). Compound (7), which was developed by Rau et al., showed reactivity when being used for ethylene polymerization and ethylene/1-hexene copolymerization at high temperature and high pressure (210° C., 150 Mpa) (J. Organomet. Chem. 2000, 608, 71). Compound (8), which has a similar structure to Compound (7), can be used for high temperature, high pressure polymerization, which was applied to US Patent Office by Sumitomo Co. (U.S. Pat. No. 6,548,686).
It was reported that a supported catalyst was synthesized and supported in the CGC form by linkage structure on a silica surface (J. Mol. Catal. A 2004, 210, 149, J. Polym. Sci. Part A: Polym. Chem. 2003, 41, 528). It was reported that the CGC catalyst was immobilized using polystyrene having an aminomethyl group as a support (Organometallics 2003, 22, 1534). However, when the catalyst is produced by such methods, a desired group has to be first linked to a support, and then all reactions have to be performed on the support. Therefore, the reaction process becomes complicated, and requires more time. Accordingly, it is difficult to apply the catalysts in commercial plant.